vue
/
mvvm


			
				
					
						
						
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							<!DOCTYPE html><html><head><meta charset="utf-8"><style>body {
  width: 45em;
  border: 1px solid #ddd;
  outline: 1300px solid #fff;
  margin: 16px auto;
}

body .markdown-body
{
  padding: 30px;
}

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}

.markdown-body a {
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}

.markdown-body a:active,
.markdown-body a:hover {
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}

.markdown-body b,
.markdown-body strong {
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}

.markdown-body mark {
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  color: #000;
  font-style: italic;
  font-weight: bold;
}

.markdown-body sub,
.markdown-body sup {
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  position: relative;
  vertical-align: baseline;
}
.markdown-body sup {
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}
.markdown-body sub {
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}

.markdown-body h1 {
  font-size: 2em;
  margin: 0.67em 0;
}

.markdown-body img {
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}

.markdown-body hr {
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  box-sizing: content-box;
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}

.markdown-body pre {
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}

.markdown-body code,
.markdown-body kbd,
.markdown-body pre,
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}

.markdown-body input {
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}

.markdown-body html input[disabled] {
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}

.markdown-body input {
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}

.markdown-body input[type="checkbox"] {
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}

.markdown-body table {
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}

.markdown-body td,
.markdown-body th {
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}

.markdown-body .codehilitetable {
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}

.markdown-body .codehilitetable tr {
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}

.markdown-body .codehilitetable pre,
.markdown-body .codehilitetable div.codehilite {
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}

.markdown-body .linenos,
.markdown-body .code,
.markdown-body .codehilitetable td {
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}

.markdown-body td:not(.linenos) .linenodiv {
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}

.markdown-body .code {
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}

.markdown-body .linenos div pre,
.markdown-body .linenodiv pre,
.markdown-body .linenodiv {
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}

.markdown-body * {
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}

.markdown-body input {
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}

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}

.markdown-body a:hover,
.markdown-body a:focus,
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}

.markdown-body hr {
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  margin: 15px 0;
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  background: transparent;
  border: 0;
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}

.markdown-body hr:before,
.markdown-body hr:after {
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}

.markdown-body hr:after {
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}

.markdown-body h1,
.markdown-body h2,
.markdown-body h3,
.markdown-body h4,
.markdown-body h5,
.markdown-body h6 {
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  margin-bottom: 15px;
  line-height: 1.1;
}

.markdown-body h1 {
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}

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}

.markdown-body h3 {
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}

.markdown-body h4 {
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}

.markdown-body h5 {
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}

.markdown-body h6 {
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}

.markdown-body blockquote {
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}

.markdown-body ul,
.markdown-body ol {
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  margin-top: 0;
  margin-bottom: 0;
}

.markdown-body ol ol,
.markdown-body ul ol {
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}

.markdown-body ul ul ol,
.markdown-body ul ol ol,
.markdown-body ol ul ol,
.markdown-body ol ol ol {
  list-style-type: lower-alpha;
}

.markdown-body dd {
  margin-left: 0;
}

.markdown-body code,
.markdown-body pre,
.markdown-body samp {
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}

.markdown-body pre {
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  margin-bottom: 0;
}

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</style><title>readme</title></head><body><article class="markdown-body"><h2 id="vuemvvm"><a name="user-content-vuemvvm" href="#vuemvvm" class="headeranchor-link" aria-hidden="true"><span class="headeranchor"></span></a>剖析Vue实现原理，实现一个MVVM</h2>
<blockquote>
<p>本文主要是在分析Vue源码的基础上，对其相关核心思想和逻辑进行简化，并通过实现一个简单的实现来阐述相关原理和思想，文中并不会涉及太多源码片段的解析，但其核心思想都会在文中表现出来，对阅读Vue源码会有更好的帮助，相信会让你的思路更加清晰~</p>
</blockquote>
<h4 id="1vuehello-world"><a name="user-content-1vuehello-world" href="#1vuehello-world" class="headeranchor-link" aria-hidden="true"><span class="headeranchor"></span></a>1、一个简单的Vue例子：<a href="///E://personal/%E5%89%8D%E7%AB%AF/mvvm/vue-demo/index.html">Hello World!</a></h4>
<p><strong>code:</strong> <br />
<pre><code>&lt;div id=&quot;vue-app&quot;&gt;
    &lt;input type=&quot;text&quot; v-model=&quot;word&quot;&gt;
    &lt;p&gt;{{word}}&lt;/p&gt;
    &lt;button v-on:click=&quot;sayHi&quot;&gt;change model&lt;/button&gt;
&lt;/div&gt;

&lt;script src=&quot;http://cdn.bootcss.com/vue/1.0.25/vue.js&quot;&gt;&lt;/script&gt;
&lt;script&gt;
    var vm = new Vue({
        el: '#vue-app',
        data: {
            word: 'Hello World!'
        },

        methods: {
            sayHi: function() {
                this.word = 'Hi, everybody!';
            }
        }
    });
&lt;/script&gt;
</code></pre></p>
<h4 id="2my-mvvm"><a name="user-content-2my-mvvm" href="#2my-mvvm" class="headeranchor-link" aria-hidden="true"><span class="headeranchor"></span></a>2、如题，今天要跟大家分享的就是实现上面的功能，是这样子的：<a href="///E://personal/%E5%89%8D%E7%AB%AF/mvvm/mvvm.html">My mvvm</a></h4>
<p><strong>code:</strong><br />
<pre><code>&lt;div id=&quot;mvvm-app&quot;&gt;
    &lt;input type=&quot;text&quot; v-model=&quot;name&quot;&gt;
    &lt;input type=&quot;text&quot; v-model=&quot;child.name&quot;&gt;
    &lt;p v-class=&quot;className&quot; class=&quot;abc&quot;&gt;
        {{child.child.name}}
    &lt;/p&gt;
    &lt;span v-text=&quot;child.name&quot;&gt;&lt;/span&gt;
    &lt;p v-html=&quot;child.html&quot;&gt;&lt;/p&gt;
    &lt;button v-on:click=&quot;clickBtn&quot;&gt;change model&lt;/button&gt;
&lt;/div&gt;

&lt;script src=&quot;./js/observer.js&quot;&gt;&lt;/script&gt;
&lt;script src=&quot;./js/watcher.js&quot;&gt;&lt;/script&gt;
&lt;script src=&quot;./js/compile.js&quot;&gt;&lt;/script&gt;
&lt;script src=&quot;./js/mvvm.js&quot;&gt;&lt;/script&gt;
&lt;script&gt;
    var vm = new MVVM({
        el: '#mvvm-app',
        data: {
            name: 'hello ',
            className: 'btn',
            spanText: 'hello world!',
            child: {
                name: '孩子名字',
                html: '&lt;span style=&quot;color: #f00;&quot;&gt;red&lt;/span&gt;',
                child: {
                    name: '孩子的孩子名字 '
                }
            }
        },

        methods: {
            clickBtn: function(e) {
                var randomStrArr = ['childOne', 'childTwo', 'childThree'];
                this.child.name = randomStrArr[parseInt(Math.random() * 3)];
            }
        }
    });
&lt;/script&gt;
</code></pre></p>
<h4 id="3"><a name="user-content-3" href="#3" class="headeranchor-link" aria-hidden="true"><span class="headeranchor"></span></a>3、目前实现数据绑定的几种做法</h4>
<blockquote>
<p>观察者模式（backbone.js）</p>
<p>脏值检查（angular.js） </p>
<p>数据劫持（vue.js） </p>
</blockquote>
<p>观察者模式一般通过sub, pub的方式实现数据和视图的绑定监听，更新数据方式通常 <code>vm.set('property', value)</code>, 这种方式现在毕竟太low了，我们更希望通过 <code>vm.property = value</code>这种方式更新数据，同时自动更新视图。</p>
<p>angular.js 是通过脏值检测的方式比对数据是否有变更，来决定是否更新视图，最简单的方式就是通过 <code>setInterval()</code> 定时轮询检测数据变动，当然Google不会这么low，angular只有在指定的事件触发时进入脏值检测，大致如下：</p>
<ul>
<li>DOM事件，譬如用户输入文本，点击按钮等。( ng-click ) </li>
<li>XHR响应事件 ( $http ) </li>
<li>浏览器Location变更事件 ( $location ) </li>
<li>Timer事件( $timeout , $interval ) </li>
<li>执行 $digest() 或 $apply()</li>
</ul>
<p><strong> vue.js 则是数据劫持结合观察者模式，通过<code>Object.defineProperty()</code>来劫持各个属性的<code>setter</code>，<code>getter</code>，在数据变动时发布消息给订阅者，触发相应的监听回调。</strong></p>
<h4 id="4vue-github"><a name="user-content-4vue-github" href="#4vue-github" class="headeranchor-link" aria-hidden="true"><span class="headeranchor"></span></a>4、Vue的生命周期 (<a href="https://github.com/vuejs/vue/">Github</a>)</h4>
<p><img src="https://vuejs.org.cn/images/lifecycle.png" width="640px"></p>
<h4 id="5"><a name="user-content-5" href="#5" class="headeranchor-link" aria-hidden="true"><span class="headeranchor"></span></a>5、我们要实现的关键点：</h4>
<ul>
<li>数据监听 Observer.js 和消息订阅器 Dep.js</li>
<li>订阅者 Watcher.js</li>
<li>指令编译器 Compile.js</li>
<li>入口 mvvm</li>
</ul>
<h4 id="6objectdefineproperty"><a name="user-content-6objectdefineproperty" href="#6objectdefineproperty" class="headeranchor-link" aria-hidden="true"><span class="headeranchor"></span></a>6、一切基于此Object.defineProperty()</h4>
<p><em>IE8+</em></p>
<p><strong>code:</strong><br />
<pre><code>function defineReative(data) {
    var val;
    Object.defineProperty(data, 'name', {
        enumerable: true,   // 可枚举
        configurable: true, // 不能再define
        get: function() {
            return val;
        },
        set: function(newVal) {
            console.log('你变了：', val, ' ==&gt; ', newVal);
            val = newVal;
        }
    });
}

var data = {};
defineReative(data);
</code></pre></p>
<h4 id="7observerjs"><a name="user-content-7observerjs" href="#7observerjs" class="headeranchor-link" aria-hidden="true"><span class="headeranchor"></span></a>7、实现Observer.js</h4>
<p>负责监听源数据所有属性，一旦发生变化，通知订阅者更新视图</p>
<p><a href="///E://personal/%E5%89%8D%E7%AB%AF/mvvm/js/observer.js">code</a></p>
<h4 id="8compilejs"><a name="user-content-8compilejs" href="#8compilejs" class="headeranchor-link" aria-hidden="true"><span class="headeranchor"></span></a>8、实现Compile.js</h4>
<p>负责解析模板指令，不同的指令绑定不同的处理回调及视图更新方法</p>
<p><a href="///E://personal/%E5%89%8D%E7%AB%AF/mvvm/js/compile.js">code</a></p>
<h4 id="9observe-compile-watcherjs"><a name="user-content-9observe-compile-watcherjs" href="#9observe-compile-watcherjs" class="headeranchor-link" aria-hidden="true"><span class="headeranchor"></span></a>9、如何连接observe 和 compile &ndash;&gt; watcher.js（桥梁）</h4>
<p>充当数据更新的订阅者，每一个属性的变化都会通知它，在compile阶段实例化并注入回调函数</p>
<p>每一个属性都有一个watcher</p>
<p><a href="///E://personal/%E5%89%8D%E7%AB%AF/mvvm/js/watcher.js">code</a></p></article></body></html>